This invention relates to an illuminator, especially a runway approach flashlight, for forming a directable, generally rectangular light beam, comprising a light source, such as a xenon lamp, an illuminator body, and a reflector supported to it and comprising a generally cup-like rear reflector fitted behind the light source.
Finish Published Specification 66074, for instance, discloses an illuminator of substantially the above-described type for similar purposes. The runway approach flashlight according to the invention should radiate a flashing light so as to form a beam having the shape of a horizontal rectangle in cross-section. This beam has to be directed at a predetermined angle with respect to the horizontal plane. Within the area of the beam, the effective light intensity values have to be adjustable in compliance with various specifications both as concerns the width of the beam and the maximum/minimum ratio of the intensities. In the above-mentioned known arrangement, the illuminator with its casing has been made tiltable for directing the beam by providing the back portion of the casing with a joint with respect to which the front edge of the casing can be lifted by means of an adjusting screw. This way of adjustment requires that the electronics controlling the illuminator unit should be placed in a housing separate from the illuminator in order that the tiltable structure would not be too heavy and clumsy. On the other hand, the directing of this kind of illuminator, that is, the adjustment of the angle of tilt, has to be checked at least after the illuminator has been installed e.g. on a light support possibly several meters above the surface of the earth. In this known arrangement, the light beam itself is shaped by an elliptical rear reflector and optical means positioned in front of a light source. The light distribution in the illuminator is fixed and cannot be adjusted in compliance with various specifications, but possible changes in the distribution of light have to be made by modifying the structure of the illuminator unit itself.